Synthetic hematocrit derived from the longitudinal relaxation of blood can lead to clinically significant errors in measurement of extracellular volume fraction in pediatric and young adult patients

The orientation of MRI-measured diffusion tensor in the myocardium has been directly correlated to the tissue fiber direction and widely characterized. However, the scalar anisotropy indexes have mostly been assumed to be uniform throughout the myocardial wall. The present study examines the fractional anisotropy (FA) as a function of transmural depth and circumferential and longitudinal locations in the normal sheep cardiac left ventricle. Results indicate that FA remains relatively constant from the epicardium to the midwall and then decreases (25.7%) steadily toward the endocardium. The decrease of FA corresponds to 7.9% and 12.9% increases in the secondary and tertiary diffusion tensor diffusivities, respectively. The transmural location of the FA transition coincides with the location where myocardial fibers run exactly circumferentially. There is also a significant difference in the midwall-endocardium FA slope between the septum and the posterior or lateral left ventricular free wall. These findings are consistent with the cellular microstructure from histological studies of the myocardium and suggest a role for MR diffusion tensor imaging in characterization of not only fiber orientation but, also, other tissue parameters, such as the extracellular volume fraction.

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Timing of post contrast T1 values affects the extracellular volume fraction in ST segment elevation myocardial infarction

Journal of Cardiovascular Magnetic Resonance ◽

10.1186/1532-429x-17-s1-p126 ◽

2015 ◽

Vol 17 (S1) ◽

Author(s):

Elisa McAlindon ◽

Chris B Lawton ◽

Chiara Bucciarelli-Ducci

Keyword(s):

Myocardial Infarction ◽

Volume Fraction ◽

Extracellular Volume ◽

Extracellular Volume Fraction ◽

Post Contrast ◽

St Segment Elevation ◽

Segment Elevation Myocardial Infarction ◽

St Segment

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In patients with acute myocarditis, the difference in apparent extracellular volume fraction between affected and healthy myocardium does not differ between early and late post-contrast imaging

Journal of Cardiovascular Magnetic Resonance ◽

10.1186/1532-429x-18-s1-p246 ◽

2016 ◽

Vol 18 (S1) ◽

Author(s):

Magnus Lundin ◽

Peder Sörensson ◽

Peter Kellman ◽

Andreas Sigfridsson ◽

Martin Ugander

Keyword(s):

Volume Fraction ◽

Acute Myocarditis ◽

Extracellular Volume ◽

Extracellular Volume Fraction ◽

Contrast Imaging ◽

Post Contrast ◽

Healthy Myocardium ◽

The Difference

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Abstract 17263: Pre-Clinical Left Ventricular Myocardial Remodeling in Patients With Friedreich’s Ataxia: A Cardiac MRI Study

Circulation ◽

10.1161/circ.138.suppl_1.17263 ◽

2018 ◽

Vol 138 (Suppl_1) ◽

Author(s):

Karen A Takazaki1 ◽

Thiago Quinaglia A. C. Silva ◽

Alberto Martinez ◽

Tomas Neilan ◽

Ravi SHAH ◽

...

Keyword(s):

Heart Failure ◽

Volume Fraction ◽

Extracellular Volume ◽

Extracellular Volume Fraction ◽

Friedreich’S Ataxia ◽

Left Ventricular ◽

Friedreich's Ataxia ◽

Intracellular Water ◽

Lv Mass ◽

Burn Out

Background: Heart Failure (HF) is the most common cause of death in Friedreich’s ataxia (FRDA), an inherited mitochondrial disease. Myocardial fibrosis is a well-documented histopathological feature among FRDA patients with HF. Objectives: In this study we will investigate the myocardial extracellular volume fraction (ECV) and intracellular water lifetime (τ ic ), using T1-weighted CMR imaging, in a cohort of patients with FRDA without signs of heart failure. We will also investigate whether myocardial tissue phenotyping by CMR can highlight particular characteristics of LV remodeling in FRDA’s cardiomyopathy, beyond those currently assessed with imaging-based classification of disease severity. Methods: Twenty-six FRDA’s patients (age 26.6±9.3 years, 15 women) without signs of HF, and 10 healthy controls (32.6±7.3 years, 5 women) underwent cardiac magnetic resonance (CMR) studies for assessment of left ventricular (LV) function, myocardial T1, late gadolinium enhancement (LGE), extracellular volume fraction (ECV), and intracellular water-lifetime (τ ic ) as marker of cardiomyocyte size. Neurological decline was determined using the FRDA rating scale (FARS 3). Results: FRDA patients had normal LV ejection fraction (LVEF: 67.66±11.4 vs. 63.9±9.0, P=0.311), larger LV mass index (LVMASSi: 61.03±22.1 vs. 45±4.2g/m 2 , P<0.001), and decreased LV end-diastolic volume index (LVEDVi 53.42±12 vs. 75.7±16.1, P=0.002), compared with controls. ECV and τ ic , were increased in FRDA patients (ECV: 0.36±0.05 vs. 0.25±0.02, P<0.0001; τ ic : 0.13±0.07 vs. 0.06±0.03, P=0.001). ECV was positively associated with LV mass-to-volume ratio (r=0.628, P<0.001). FARS 3 correlated positively with disease duration (r=0.669, P<0.001), and negatively with τ ic , (r=0.478, P=0.039). LVMASSi and cardiomyocyte mass-index [(1–ECV)LVMASSi] declined with age, indicating that LV hypertrophy may transition to a “burn-out” phase with LV atrophy. Conclusions: LV hypertrophy in FRDA reflects an expansion of the myocardial interstitium and an increase in cardiomyocyte size. In contrast, the neurological decline was more likely with decreasing cardiomyocyte size, possibly an early sign of myocardial “burn-out” in FRDA.

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